Switch



March 31,- 19.31.

J. A- OBERMAIER SWITCH 2 ShetS-Sheet l Filed Dec. 9, 1927 20 211 [53 l36 4222 3f @Mam March 3l, 1931. J. A..oBr-:'RMA|ER SWITCH Filed Dec, 9, 1927 2 Sheets-Sheet 2 Patent-ed Mar. 31, 1931 UNITED STATES PATENT OFFICE JOHN A. OBERMAIER, OF CHICAGO, ILLINOIS SWITCH Application filed December 9, 1927. Serial No. 238,738.

My present invention relates to electrical every fifteen minutes. This means a large measuring instruments for measuring the number of operations of the selector switch. characteris ics of :1 plurality of circuits, and There are numerous other situations where is more particularly concerned with the such plurality of circuits are employed as, for

5 switch for switching the measuring instruexample, in multideck baking ovens, heat 5 ment from one circuit to another and the treating furnaces and the like.

mounting' of the switch either in the case of In the production of the present switch, I

the instrument or in a separate case. have aimed to meet the requirements of a defi- In the specific embodiment herein shown nite constant contact resistance and of such a and described,amillivolt meter is arranged to design as to be small enough to go into the 39 be connected to a plurality of pyrometer cirinstrument case.

cuits by a selector switch. The meter is grad- In order to secure the desired constant conuated in terms of temperature or any variable tact resistance, I have eliminated wiping or which is a function of the same. I employ hammering of the contacts. I provide means an instrument of relatively low resistance, for separating the contacts byalifting action 65 i. e., of the order of l0 to 50 ohms. The pyand engaging them by an abutting contact rouieter elements may give a. potential up to which is thereafter put under relatively 50 millivolts. Now it may be seen that'if any heavy pressure, as by a cam or toggle action.

change of resistance in the instrument circuit l/Vhen so engaged, the contacts, are held is caused by variations of contact resistance against any relative rotary motion by an in- 70 in the selector switch, the accuracy of the indexing mechanism which thereby prevents dication is lost. wear.

I have experimented with various forms of The specific mechanism which I shall deswitches now known and find that a wiping scribe secures a slight rolling action after the contact is not satisfactory, as it changes its contacts are once engaged, which rolling ac- 75 resistance due to wear in use. The rubbing tion is enough to insure, Cutting 0f my p0SSi of the parts changes the surface Contact. ble film on the surfaces, with a minimum of llien the parts are of copper or the like, the wear. This specific forni of contact may be metal. surfaces tend to score and become varied.

rough. The result is that the contact resist- Also I provide an improved mounting for eo ance does not remain constant. The absolute the selector switch in the instrument case lo value of the contact resistance is immaterial, malte a convenient assembly and to arrange so long as it is constant. Such wearing 01 the the mounting of thc switch to free the instrumetal parts also produces a powdered metal nient from disarrangcmeiit or stress due to which deposits between contacts and may operation of the switch.

.shunt or short circuit some of the circuits. Numerous other features of improvement Systems of this kind, i. e., pyrometer syswill be apparent from the following detailed tems wherein apluraity of pyrometer eledescription and drawings. ments are mounted in different locations and In order to acquaint those skilled in the art arranged to be read from a common instriiwith the manner of constructing and operat- 90 nient are now employed in many different siting a device embodying my invention, I shall nations. For example, in checking the operdescribe iii connection with the acconipanyation of Diesel engines, it is now the practice ing drawings a specific embodiment of my iiito insert a pyrometer thermocouple in the eX- yention.

haust of each cylinder to determine the rela- Fig. l is a plan View, partly diagrammatic, 95

tive work done by the cylinders and the eiof a system employing my invention; ciency of combustion. In suoli case it is com- Fig. 2 is a front elevational view of the nion to have the instrument graduated dimetering instrument having a switch of my rectly in horsepower. When so employed, it invention embodied therein; n 00 is customary to take a reading of each circuit Fig. 3 is a section taken on the line 3 3 of 100 Vment l is relatively low and. hence, anT

Fig. 4L showing the metering element'V and afi-ame plate 17, preferably of metal, and a part of the switch in elevation;

Fig. l is a view taken on the line e of Fig. r3 with the casing broken away to reveal the switch and its mounting inside of the casine;

Fig.4 5 is an enlarged sectional view taken on the line 5 5 of Fig. 3 g' F ig. 6 is a transverse section through'the switch taken on the line 6 6 of Fig. 5;

Fig. 7 is a rear elevational view of the switch as seen on the line 7 7 of Fig. 5;

Fig. 8 is a cross-sectional fragmentary view taken on the line 8 8 of Fig. 7;

Fig. 9 is a cross-sectional view taken on the line 9 9 of Fig. 5;

Fig. 1() is an end view of a modified form of the switch,

iig. llfis a fragmentary sectie-nal vieuv of a modified form or mounting the switch handie; and

12 is a plan View of a pointer secured to the shaft shown in Fig. 11.

Referring to F ig. 1,1 have shown aseries of six thermocouplesTl to T6, inclusive, such as might, for example, be disposed in the proper relation to siX Diesel engine cylinders, each of these thermocouples having a. separate circuit terminating in suitable terminals within the indicating instrument l on the selector switch S. l

v The instrument I is a millivoit meter graduated in suitable terms, dependent upon what it desired to ascertain fr the action of the thermocouples.

rlhe indicating instrument 1 has a movable indicating pointer 1 actuated by a suitable coil'2 which is adapted through the selector switch S to be connected to the c'rcuit of the thermocouples, such as T1.

rlhe features of construction of the indicating instrument I are not important in the present invention. except as they permit the selector' switch Si to besuitabiv onibodic within the same case or other ilo ient relationship to the instriunent. .es I have heretofore indie the resisi ance of the coil in the ind* no' instruchange in resistance in the switch would entail a larger percentage variation in the accuracy of the instrument. y

The instrument I includes the permanent magnet 3 having pole pieces and 5 all constructed in. accordance with my l) tent No. 1,597,327, August 24, 1927. he selector switch S has an operating handle 10 mounted on a shaft 11 and provigded with a suitable pointer 12 playing over` the chart 13, which chart is7 in reality, suitable numbers or other symbols stamped on the face 13 of the flanged bushing i3 and secured in the top wall of the case 15.V

lThe shaft 11 is supported in the switch frame, which is constructed of an upper lower frame plate 18, preferably of insulating material.. rhese frame plates are connected together by posts or pillars 19 1S), suitable screws 20 20 passing through the top frame plate 17 and being threaded into the posts 19 19 at the upper en d. The posts 19 19 may be threaded into the lowerframe plate 18, or the said frame plate may be clamped against shoulders on the pillars 19 19 as by clamping nuts 20 20, said pillars 19 19 having reduced ends forming pins 21 21 seating in sockets formed in the blocks 22 22 secured to the bottom or base plate 23 of the indicating instrument.

The bottom or frame plat 23 of the indicating instrument has an extending flange 211 terminating in a cylindrical wall 25, and theV case or cover 15 has cooperating flange closely fitting the walls 2li and 25 of the'base plate so as to secure the cover in substantially a dust proof manner to the base plate; Suitable screws, shown at 25, pass through the flange of the cover and are threaded into theA wall 2a of the base plate to hold these parts together. l

The shaft 11 passes through the boss or hub 27 of the bushing 1li and if desired, a spacing Washer 28 lies between said boss and the top frame plate 17 of the switch. rThe bushing 11i preferably contains a packing.;l material 29 disposed'in suitable recess so as to provide a dust and moisture proof paching Jfor the shaft. l

It will now beiseen that the switch S has a three point suspension in the case, i. e., one point of suspension on the shaft 11 where it passes through the bushing 12S-3, and the other tivo points of suspension being on the pins 2.1 21 in the sockets in the blocks and 23. in this way the switch is held .in the oase and on the base plate relatively loosely, so that in assembling the instrument no can be lput upon the base plate and cover and thus disturb thev indicating instrument and frictionless opera-tion of the switch. Also, the assembly may be made in units, thatris, the indicating instrument may be made up and assembled as one unit and the switch as a separate unit. This also facilitatesy inspection or repair of the switch` without tearingT down the instrument.

rEhe shaft 11 has two proper motions, one rotary motion or selecting motion to select the circuit, and the second motion is an axial motion to close the circuit with the selecting contacts. Y

The contacts are mounted on the insulating plate 18 in pairs, the pairs being disposed at opposite ends of a diameter, passing through the shaft 11. rlhus, in Fig. 5 contacts 30 3O constitute a pair which are connected to the circuitof one-of the thermon couples such as T1.

l have shown six sets of contacts `thus ar n il:

ranged to provide terminals for the six thermocouple circuits although there is no limit to the number that may be employed.

These contacts are formed as shown in Fig. 5, constituting head portions 31 and shanks 32 passing through holes in the insulating plate 18 and being riveted at the back to hold a contact firmly in position.

The terminals of the circuits are soldered to the riveted ends of the shanks 32 on the back side of the plate 18.

The terminals of the instrument coil 2 are connected to a pair of movable contact members 33-34 mounted in a supporting member 35, which comprises a plate of insulating material, such, for example, bakelized fiber or cloth. These contacts 33-31 comprise relatively short cylindrical pins projecting through holes in the movable plate and having rounded ends adapted to abut with the heads 31 of the contacts such as 30-30.

The plate 35 is pinned or otherwise secured to the end of the shaft 11, as shown in Fig. 5, and the plate 35 and shaft 11 are urged downwardly, as viewed in Fig. 5, by a compression spring 36 interposed between the plate 35 and the insulating frame plate 18 and embracing the shaft 11. The spring 3G might be disposed at any other suitable point, for example between framefplate 17 and star wheel 50.

The movable pins 33 have rounded ends adapted to be brought into abutting contact with the head 31 of the pins 30. On the lower side of the plate 35 the pins 33 have reduced studs 37 which extend through springs 38 and are there riveted in place.

The springs 38 are of curved form adapted to lie along the edges of the plate 35 to carry the pins at diametrically opposite points in the plate free to slide in the plate 35 and yet held under suitable Spring pressure. The ends of the springs 38 are anchored under clamping plates v10-40, these clamping plates being held preferably by screws passing through the insulating plates 35.

L-shaped brackets A,t1-11 extend from the clamping plates toward the center of the movable frame plate 35, the ends l12-/12 cxtending in axial parallel relation, as shown in Fig. '6. To these ends 4t2 42 spiral conducting rivets 13-43 are connected, and the outer ends of the spiral conducting rivets i3-43 are anchored to conducting brackets lll-414, the bases of the brackets being held by the screws A15-15 threaded into the stationary frame plate 18. The terminals of the coil 2 are suitably connected to the screws 4.5. or to the brackets 44.

The shaft 11 is adapted to be moved endwise by means of the handle 10, this handle being pinned at 46 to the end of the shaft, and the lower end of the handle where it is pivoted to the shaft being provided with a cam surface 47 and a square end 48. An antifriction plate or washer 49 may be disposed immediately under the handle member l to take the thrust imposed by the cam action along said handle.

The washer 19 is loose on the shaft 11, but the pointer member' 12 is fastened thereto.

IhereaS, in Figs. 1, 2 and 5, I have shown the end of the shaft 11 as flattened or slabbed oli' at the sides and the handle 10 forked to embracel the same, the handle may be slabbed oli' at the sides and the' shaft forked as shown in Fig. 11. In that event the pointer formed of a corresponding configuration as shown in Fig.

Now, in order to prevent accidental wiping contact of the pins 33-34 with the contacts -30 and the like, I provide an indexing .mechanism and registering mechanism for first registering the contacts 33-34 with a particular pair of the contacts 3030 and then lock the shaft 11 against rotary motion as soon as it starts endwise motion. For the purpose of registering the movable contacts 323-34-, I provide a star wheel 50 which has a hub 51 pinned to the shaft 11, as shown in Fig. 5. This star wheel has two teeth 52 at opposite ends of a diameter forming stops for the rotary motion of the shaft 11.

A spring pressed roller 53 is adapted to spring into the notches between the teeth on the star wheel so as to register the contacts 33--34 accurately with the stationary contacts 30-30. The roller 53 is held on a pin 5/1, this pin at its outer end extending into a slot 5G in the frame plate 17 and at its inner end being mounted relatively fixedly in the bearing block 55. The block 55 in turn' is secured to the upper end of a spring 57, which spring is bowed and isprovided with a lower securing base 58 which is secured to the in sulating frame plate 18 as shown in Fig. 5. N ow it can be seen that with the handle in full line position as shown in- Fig. 5, the shaft 11 may be turned and the registering mechanism will accurately register the Ino\'- able contacts 33-3el with a stationary contact such as 30-3 The teeth 52-52 which are longer than the other teeth on the star wheel 50, will not pass under the roller 53, since it is limited in its outward motion by the limited play of the pin 54k in the slot 56.

To interlock the shaft 11 against rotary motion and to index the shaft accurately, I provide a pair of indexing pins or posts 59-59. These posts are provided with extending pins riveted into the upper frame plate 17. Y

Now it can be seen that the endwise motion of the shaft 11 moves the star wheel 5() with it, and the post or pins 59-59 enter the notches between adjacent teeth of the star wheel so as to prevent rotary motion after endwise motion has once begun.

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the stationary contact 30. The ends of thesev pins are roundedand the pins Sil-34e yare relatively loose in the plate 85. YWhen the plate 35 is drawn towards the stationary frame plate 18, these pins, which are mounted in the curved spring 38-38 have a relatively outward motion with respect to the movable plate 85 and, at the same time, have a slight angular` motion due to the bending of the spring S-3S. The result is, that the very slight angular mot-ion which they have, tends to give a wiping action of small extent but of great effectiveness. This tends to cut any film which might be found on any of the contacting parts.

T he springs iS-88 are made relatively stiff and with the cam action of the handle l0 a very considerable pressure is secured between the movable and stationary contacts. The handle l() is adapted to remain in raised position, as shown in dotted lines in Fig. if so desired.

The operation of the device is, briefly, as follows:

l/Vith the instrument as shown connected in Fig. l, thehandle member l() is moved to bring the pointer l2 into register with the points on the card 13. A definite click action secured by the roller 53 on the spring 57 so that the pointer is easily registered with the desired point on the card. Then the handle 10 is swung into line with thesliaft ll to close the contact, and the reading may then be made onthe instrument I.

The spring held roller 53, indropping be` tween the point-s of the star wheel, holds the star wheel in reOister with the indexin T ins" Then to close the circuit, the handle l0 is swung intoV the upright position, throwing the shaft 1l endwisc against the tension of the spring 36 until the contacts eul age contacts such as 3U-30, whereupon the .esistance of the springs 3S-38 is en-`V countered. Y

As the springs 38-38 yield', the pins have a slight rockin@ action which breaks any b e: n b v l I.. hlm on the surrace of the coo ieratina parts l n i and brings the terminals 33 34- ifirinly into engagement with the terminals 30-3O closing` the circuit between the selected thermo-` couple and the instrument.

Thus vthe thermocouples may be connected to the'instrun'ient and readings taken iroin a central point with rapidity and facility.

Due to lifting of the movable contacts clear of the stationary contacts no cross connection between contacts can occur. This makes the switch valuable for conditions where a wiping contact could not be used, as for exam le in measuring voltages in circuits of considerable potential and other uses.

While I have shown two sets of contacts 30-30, it is to be understood that one termi nal of each of the thermocouples may be connected to a common terminal, for example, the ring terminal 60, as shown in'Fig. l0. In this case there are twelve individual contacts Gl and the common contact 60, so that twelve circuits may be connected by the selector switch. In this case the spring 38 is mounted in a radial position to bringl its pin 33 above the row of contacts 6l, and the spring is arranged around the edge of the movable plate Se which corresponds to the plate 35, as shown in Fig; 5, so as to bring' the contact pin 65 diametrically opposite the contact pin 33 and yet over the ring`- contact 60.

is to be observed that the flexible spiral rivet 43 permits not only the rotary motion which is require-d, but also the axial motion which is required.

In the form shown in Fig. l0, the indexing mechanism will permit of substantially a complete revolution, only one of the points being long enough to form a stop.

There is no iinierent limitation on the number Yofy selectable contacts that may be eingloyed. v V Y I do not intend to be limited to the details shown and described, except as the are specifically included in the claims.

I claim l. InV a selector switch, a group of relative-ly stationary contacts arranged in YJthe arc of a circle, a shaft having a rotary motion and axial motion, a selector contact carried by theV shaft normally out of contact with the stationary contacts, indexing means including a star wheel on saidshaft and cooperating movable and stationary pins for locking the shaft in position to register the selector contact with any predetermined one of said stationary contacts, and means to move the shaft axially to cause abutting engagement of the selector contact with the predecontact normally out of engagement with the stationary contacts, a support for the selector contact movable in one path to bring the selector contact into'register with the selected one of said stationary contacts, means for moving the support in another path to bring the movable Contact into abutting relation to the selected contact, the selected stationary contact limitino' the movement of the movable contact in its second path, and means to loclr the support against motion in said one path after it enters the second path.

3. In a selector switch, a supporting frame, a shaft supported therein for rotary and axial motion, a plurality of relatively stationary contacts arranged in the arc of a circle about said shaft, a selector member carried by the shaft for closing a circuit through any predetermined one ofsaid rela- Cil tively stationary contacts, indexing means including a star Wheel on the shaft and a spring roller cooperating therewith for registering the shaft in predetermined position, and a cam lever for moving the shaft rotarily to select the predetermined stationary contacts, said lever being pivoted to the shaft for moving it axially to cause the selector member to close the circuit of the desired stationary contact.

4. In combination with a plurality of thermal responsive elements, a common indicating instrument, and circuits for said elements terminating in contacts, of a selector switch embodying said contacts, said contacts being arranged in the arc of a circle, a rotatable shaft, a selector contact carried by said shaft and adapted to lie at the same radial distance from the shaft as said first named contact, spring means for the selector contact, and indexing mechanism for the shaft for registering the se-lector contact with the stationary contacts, means for moving` the shaft endivise to bring the selector contact into engagement with the first-named contact, said indexing means locking the shaft against rotary motion When it is moved endvvise.

5. In combination, a shaft, a group of contacts arranged in a common radius about the shaft, a seiector contact carried by the shaft normally out of engagement With the stationary contacts, means for registering the selector contact with the stationary contacts one at a time, and indexing means including a star Wheel on the shaftfor locking the shaft against rotary motion when the shaft 1s moved endwise, said locking mechanism being effective before the selector contact engages the stationary contact.

6. In combination, a pair of frame plates, one of said plates carrying a plurality of contacts in insulated relation, a shaft having bearings in said plates, said shaft having rotary motion and axial motion, a selector contact normally carried out of engagement with the stationary contacts, and a common handle on the shaft for rotating the same to bring the selector contact into register With one of said stationary contacts and for moving the shaft endwise to bring the selector contact into engagement with the selected one of the stationary contacts, said handle including cam means for moving the shaft endwise and then locking it.

7. In combination, a shaft, a carrier of insulation mounted on one end of the shaft, a group of stationary contacts arranged in a circle about the shaft, a selectorcontact carried on the carrier member, a flat spring connecting the contact to the carrier member, said selector contacthaving a slight angular motion when it engages the selected stationary contact While bending of the flat spring, and means on said shaft engaged by pins flexibly mounted with respect to said stationtension of said flat spring.`

8. In combination, a fra me member, a sha ft projecting through the frame member, a circular series of contacts disposed on the frame member about the shaft, a plate of insulating material carried on the end of the shaft, said plate forming a carrier for a selector Contact, a selector contact con'iprising a pin projecting through said plate, a spring securedv at one end tothe plate and at theother end to the selector contact, a spiral conducting ribbon, a bracket connecting the inner end of the ribbon to the spring, and the bri cket mount- -ed on the frame plate and connected to the outer end of the spiral ribbon. f

9. In combination, a base plate having an indicating instrument mounted thereupon, a cover member for the instrument, said cover` member cooperating with the base plate, a pair of sockets mounted on the base plate, a bushing in the cover, a select-or switch having a frame, bolts projecting from the frame and extending into said sockets and having a shaft projecting through said bushing.

l0. In combination, Aa frame, a circular group of stationary contacts, a selector contact carried by the frame normally out of contact With the stationary contacts, a shaft projecting through the frame and carrying said selector contact, a handle pivoted to the shaft, saidhandle having a cam-shaped extension .A for moving the shaft endwise on motion of the handle about its pivot to bring the selector contact into engagement ivith the stationary contact and for locking it in engagement therewith, and indexing means for registering the selector contact with any one of the predetermined stationary contacts, said means including indexing' pins on the side of the frame opposite the side Wherethc handle is mounted for locking the shaft against rotary motion While the contacts are engaged.

11. In combination, a frame, a plurality of stationary contacts arranged in a circular group on the frame, a shaft centrally of said group mounted in the frame, a selector contact carried by the shaft normally out of engagement With the stationary contacts, a star Wheel mounted on the shaft, a spring pressed roller having limited motion for engagin the star Wheel to cause registration of the selector contact with any one of the stationary contacts, and means on the shaft for rotating the same and for moving the shaft axially to bring the selector contact into abutting relation With the selected one of the stationary contacts.

tionary contacts individually, a star Wheelv lun lill

lili! mounted on the shaft, a spring pressed roller mounted on the frame and adapted to engage the star Wheel to register the selector Contact With a predetermined one of the stationary contacts, means to rotate the shaft to bring the selector contact into'register with a predetermined one of the stationary contacts, means to move the shaft axially, and indexing pins adapted to enter between the points of l 10 the star. wheel when the shaft is moved axiall f.

153. In combination, an electrical indicating instrument, a base plate for supporting instrulnent, a cover for the instrument, said cover having a flange cooperating With the base plate, said cover having a bushing, said bushing having a projecting margin forming a chart having indications kthereupon, a

switch mounted within the cover and having an operating shaft movable axially and rotarily projecting through the bushing, a

handle pivoted on the end of the shaft outlside of the cover, a pointer connected to the shaft, said handle adapted to be disposed substantially at right angles to the shaft for rotating the shaft to bring lthe pointer into alignment with the points on the card, and

having cam means adapted to be actuated by pivotal motion of the handle on the shaft to move the shaft endwise to close the circuit of the instrument through said switch.

14,-. In a switch of the class described, Va pair of frame plates, postsconnecting the frame plates, a circular row of contacts, a shaft extending` through the frame plates and disposed centrally of said stationary contacts, a

selector contact carried by the shaft, said shaft having rotary and axial motion, a star wheel on the shaft, spring means mounted on one of the plates and extending towards the other plate, a pin mounted on the spring and extending through the other frame plate, said latter frame plate having a slot for receiving the pin, and a roller on the pin adapted to drop between the points of the star Wheel.

' In witness whereof, I hereunto subscribe my name this 29 day of November, 1927.

JOHN A. OBERMAIER. 

